Aripiprazole is a newer atypical antipsychotic agent used for effective treatment of schizophrenia. It significantly reduces unwanted side effects of older typical antipsychotics by targeting, with high affinity, dopamine D2/D3 and serotonin 5-HT1A/5-HT-2A receptors. Its documented mechanism of action makes it an unlikely agent to cause syndrome of inappropriate antidiuretic hormone secretion (SIADH). We present the first reported case of SIADH caused by aripiprazole in a patient with history of schizophrenia without other precipitating factors to explain hyponatremia or SIADH.

Over the last decade, one group of neurohormonal markers, including atrial natriuretic peptide (ANP), N-terminal pro-ANP, B-type natriuretic peptide (BNP), and N-terminal proBNP, has generated much interest in the evaluation and management of heart failure and acute coronary syndrome. There has been so much literature on the subject, especially concerning BNP and proBNP, that it leaves us confused at times about what the literature has to say about these markers. In this article, we have made an honest attempt to examine all the available literature in relation to the impact of BNP and proBNP on cardiovascular disease and present it to the reader in an assimilated fashion.

BackgroundInfective endocarditis (IE) has been reported as a common complication of community acquired S. aureus bacteremia (SAB). Endocarditis cases, however, are most often reported in patients with an underlying cardiac abnormality that serves as a predisposing risk factor, including valve damage from rheumatic heart disease, previous endocarditis, placement of a prosthetic heart valve, or other cardiac abnormalities. There have been reports of isolated cases of community-acquired Staphylococcus aureus leading to endocarditis in a patient with no risk factors.Case ReportA 43-year-old previously healthy Hispanic male presented to the emergency room with a 1-week history of "flu-like " symptoms, multiple petechial hemorrhages present on his abdominal skin, and a 3/6 diastolic murmur in the left parasternal area. Blood cultures grew Staphylococcus aureus in all three blood samples sensitive to nafcillin. Echocardiogram revealed severe aortic regurgitation with possible vegetations. Blood cultures continued to grow Staphylococcus aureus despite intravenous nafcillin and gentamicin. The patient was transferred to tertiary medical center for possible porcine aortic valve replacement but on operation it was found that the left coronary leaflet was completely destroyed with a subannular abscess cavity tracking toward the anterior leaf of the mitral valve. There was a small area of burrowing abscess below the left coronary leaflet, which was débrided. The right coronary leaflet was exceedingly thin-walled and resected. Several weeks after the operation the patient reports no specific complaints, with near-full level of activity.Teaching PointEndocartitis that fails to improve within 72 hours on antibiotics should raise clinical suspicion of aortic root abscess. Antibiotic coverage for 24 hours, in general, prior to operation is necessary. Surgery is the definitive treatment. Studies indicate that a more aggressive approach of radical resection of abscess and inflamed tissue with proper reconstruction with bovine pericardium, as done in our patient, yields an excellent chance or ridding the infection. This case, a rare presentation resulting in serious complications, serves as a reminder to consider a wider range of differentials even in the absence of expected risk factors.

BackgroundAripiprazole is a newer class atypical antipsychotic agent used for effective treatment of schizophrenia. It significantly reduces unwanted side effects of older counterpart typical antipsychotics by targeting, with high affinity, dopamine D2/D3 and serotonin 5-HT1A/5-HT-2A receptors. Its documented mechanism of action makes it an unlikely agent to cause SIADH.Case ReportWe present a case of a patient with schizophrenia who after starting on aripiprazole developed SIADH on the sixteenth day of treatment. After medication was discontinued, SIADH resolved and the patient's serum sodium levels returned to normal in the following days. Our research indicates this to be the first reported case of SIADH induced by aripiprazole.DiscussionAntipsychotic medications, or neuroleptics, have revolutionized the treatment and prognosis of psychotic disorders, specifically schizophrenia, in the past century. The medications are of two groups based on mechanism: typical antipsychotics and newer atypical antipsychotics. The former exclusively block the dopamine D2 receptor in the brain, while the latter additionally block serotonin receptors to a limited extent. Atypical antipsychotics include clozapine, risperidone, olanzapine, quetiapine, and, recently, aripiprazole. Aripiprazole is unique to all other atypical antipsychotic medications in that its mechanism of action includes a partial agonism at several G-protein coupled receptors, specifically the dopamine D2/D3 and serotonin 5-HT1A receptors, and antagonistic action at other serotonin receptors, such as 5-HT2A. SIADH has not been documented in the literature as a side effect of aripiprazole.Teaching PointFurther studies are required to elucidate the exact mechanism of aripiprazole in causing SIADH. This case serves to remind clinicians to assess laboratory values and clinical symptoms after initiation of new psychotropic treatment to the patient, keeping in mind differential diagnoses, which are not necessarily documented side effects of the treatment.